JP2014043949A - Motor-operated valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure stable operability by securing play of a screw feed mechanism even when a motor-operated valve is used under a high temperature environment such as a hot gas bypass passage, in the motor-operated valve opened and closed by moving a valve element relative to a valve seat by converting a rotating motion of a rotor of an electric motor (stepping motor) into a linear motion of an operating shaft by the screw feed mechanism composed of a female screw and a male screw.SOLUTION: Materials of a male screw member and a female screw member are selected so that a linear expansion coefficient in a direction vertical to an axial direction of the female screw member is larger than a linear expansion coefficient in a direction vertical to an axial direction of the male screw member. Or the male screw member and the female screw member are made of a resin material in which fibrous filler is mixed. The fibrous filler of the male screw member is mixed while oriented in the direction vertical to the axis. The fibrous filler of the female screw member is mixed while oriented in the direction in parallel with the axis.

Description

  The present invention relates to a motor-operated valve that controls the flow rate of a refrigerant such as a heat pump refrigeration cycle.

  Conventionally, as an electric valve, there exist some which were disclosed by Unexamined-Japanese-Patent No. 2004-197800 (patent document 1) and Unexamined-Japanese-Patent No. 2002-39417 (patent document 2), for example. In Patent Document 1, a male screw is formed on the rotor shaft side of the electric motor, a female screw through which the rotor shaft passes is disposed, and a valve body is provided at the lower end of the rotor shaft. Moreover, the thing of patent document 2 has a female screw formed in the rotor side of an electric motor, the male screw which penetrates the center of this rotor is arrange | positioned, and is equipped with the valve body in the lower end part of the operating shaft. Then, the rotational movement of the rotor of the electric motor is converted into a linear movement of the operating shaft by a screw feed mechanism of a female screw and a male screw, and the valve body is moved with respect to the valve seat to open and close the valve. These motor-operated valves are used in a refrigeration cycle (refrigerant piping system) of a cooling device as disclosed in, for example, Japanese Patent Laid-Open No. 5-45027 (Patent Document 3).

Japanese Patent Laid-Open No. 2004-197800 JP 2002-39417 A JP-A-5-45027

  In the hot gas bypass path of the refrigeration cycle as in Patent Document 3, the temperature of the refrigerant rises to about 120 ° C. For this reason, when the conventional motor-operated valve is used for the hot gas bypass passage, the vertical and horizontal engagement portions (screw portions) of the female screw and the male screw are different due to the difference in linear expansion coefficient between the member constituting the female screw and the member constituting the male screw. There is a problem that the play is reduced and the operability of the screw feed mechanism is deteriorated. In addition, wear powder generated by repetitive operations and other sliding parts accumulate, and the actual clearance of the screw part becomes smaller than the prescribed clearance. Furthermore, since the motor torque decreases because the magnet demagnetization and the coil electrical resistance increase at high temperatures, it is important to secure an appropriate clearance. In addition, since the strength of the material generally decreases at high temperatures, in the motorized valve used for the hot gas bypass passage, it is necessary to increase the engagement length of the screws, so the influence of the pitch deviation between the screws becomes large. These problems prevent desired operability from being obtained.

  The present invention has been made to solve the above-described problems, and even when used in a high temperature environment, the backlash of the screw portion in the screw feed mechanism of the electric valve is ensured, and stable operability is ensured. This is the issue.

  The electric valve according to claim 1 includes a female screw provided on the valve housing side and a male screw formed on the rotor side of the electric motor and disposed through the center of the female screw, and the rotational movement of the rotor of the electric motor is In the motor-operated valve that converts the linear motion of the operating shaft by a screw feed mechanism of the female screw and the male screw and moves the valve element arranged on the operating shaft with respect to the valve seat to open and close the valve, the female screw The members constituting the male screw and the members constituting the male screw are each made of a material whose linear expansion coefficient in the direction perpendicular to the axial direction of the female screw is larger than the linear expansion coefficient in the direction perpendicular to the axial direction of the male screw. It is formed.

  The motor-operated valve according to claim 2 is the motor-operated valve according to claim 1, wherein the female screw is made of a material having an axial linear expansion coefficient of the female screw and an axial linear expansion coefficient of the male screw equivalent to each other. The member which comprises and the member which comprises the said external thread were formed, respectively.

  The motor-driven valve according to claim 3 is the motor-operated valve according to claim 1, wherein a member constituting the female screw is a resin material as a base material, and a fibrous filler is added to the resin material in the axial direction of the female screw. It is characterized by being mixed so as to be in the direction.

  According to the motor-operated valve of claim 1, the male screw member and the female screw are arranged such that the linear expansion coefficient in the direction perpendicular to the axial direction of the female screw member is larger than the linear expansion coefficient in the direction perpendicular to the axial direction of the male screw member. Since the member is configured, the female screw member expands more outward than the male screw member in a high temperature environment, so that the play between the male screw member and the female screw member can be secured, and the stable operation of the screw feeding mechanism can be ensured. Can be secured.

  According to the electric valve of the second aspect, in addition to the effect of the first aspect, the expansion in the direction of the axis L is equivalent between the male screw member and the female screw member, and the pitch change in the axial direction of the male screw and the pitch change in the axial direction of the female screw. And the backlash in the axial direction of the entire screw due to the pitch change can be prevented.

  According to the electric valve of the third aspect, in addition to the effect of the first aspect, since the direction and strength of the filler can be arbitrarily selected, the linear expansion coefficient in the axial direction of the female screw and the linear expansion coefficient in the axial direction of the male screw are obtained. The linear expansion coefficient in the direction perpendicular to the axial direction of the female screw can be made larger than the linear expansion coefficient in the direction perpendicular to the axial direction of the male screw. It becomes easy.

It is a longitudinal cross-sectional view of the motor operated valve of the 1st reference example of this invention. It is a longitudinal cross-sectional view of the motor operated valve of the 2nd reference example of this invention. It is a figure which shows the example which forms the external thread member and internal thread member in embodiment with the resin material which mixed the fibrous filler.

  Next, an embodiment of the motor-operated valve of the present invention will be described with reference to the drawings. First, a reference example will be described. Even when the relationship between the female screw and the male screw with respect to the rotor of the reference example is reversed as in the embodiment described later, the same effect as the reference example can be obtained. FIG. 1 is a longitudinal sectional view of a motor operated valve of a first reference example. Note that the concept of “upper and lower” in the following description corresponds to the upper and lower sides in the drawing of FIG. The motor-operated valve of this reference example has a valve housing 1, and the valve housing 1 includes a valve chamber 1a, an inlet port 1b opened on one inner peripheral surface of the valve chamber 1a, and an axis L direction of the valve chamber 1a. An outlet port 1c opened at one end, a valve port 1d communicating with the outlet port 1c and the valve chamber 1a, and a cylindrical guide fitting hole 1e penetrating the valve chamber 1a are formed. An end of the valve port 1d on the valve chamber 1a side constitutes a valve seat 1d1. The inlet port 1b is formed as a horizontal hole, and a joint pipe 11 connected to the hot gas bypass is fixed to the inlet port 1b by brazing. The outlet port 1c is formed as a pilot hole, and a joint pipe 12 connected to the hot gas bypass path is fixed to the outlet port 1c by brazing.

  A cylindrical guide 13 is fitted in the guide fitting hole 1e in the upper part of the valve chamber 1a, and the guide 13 is fixed to the valve housing 1 by caulking the upper part of the valve housing 1. A cylindrical valve body 14 and a piston 15 are inserted into the guide 13, and the valve body 14 is attached to the lower end of the operating shaft 2 via a bearing 17. A buffering coil spring 14 a is disposed in the valve body 14. A male screw receiving portion 13a is formed at the upper end of the guide 13, and the operating shaft 2 can be slid in the direction of the axis L by the male screw receiving portion 13a, and the upper portion of the operating shaft 2 faces the stepping motor 10 described later. It is extended. A male screw member 21 having a male screw 21a is fixed to the outer periphery of the operation shaft 2 in the stepping motor 10.

  A dish-like lid case 16 is airtightly fixed to the upper portion of the valve housing 1 by brazing, and a stepping motor 10 as an electric motor is attached to the lid case 16. A cylindrical rotor case 10 a of the stepping motor 10 is airtightly fixed to the lid case 16. The rotor 3 is rotatably disposed inside the rotor case 10a. The rotor 3 includes a female screw member 31, a female screw holder 32, a coupling fitting 33, and a magnet 34 in order from the inside. The connection fitting 33 connects the female screw holder 32 and the magnet 34. An internal thread 31 a is formed inside the internal thread member 31. The male screw 31 a is screwed to the male screw 21 a on the outer peripheral surface of the male screw member 21. A stator unit 10b is disposed on the outer periphery of the rotor case 10a, and the stepping motor 10 rotates the rotor 3 according to the number of pulses when a pulse signal is given to the stator coil of the stator unit 10b. Let

  A stopper holding rod 41 is suspended and fixed inside the rotor case 10a. A spiral guide 42 is attached to the stopper holding rod 41, and a movable stopper 43 is engaged with the spiral guide 42. The movable stopper 43 is moved up and down while being swung by being guided by the spiral guide 42 as the rotor 3 rotates by being kicked around by the pin 33 a attached to the connection fitting 33 of the rotor 3. The movable stopper 43 is in contact with the stopper portion 42a at the lower end of the spiral guide 42 or the stopper portion 42b at the upper end, thereby restricting the rotation of the rotor 3 in the valve closing direction or the valve opening direction.

  With the above configuration, when the stepping motor 10 is driven, the rotor 3 rotates within a range regulated by the movable stopper 43 and the stopper portions 42a and 42b. The rotation of the rotor 3 is converted into a linear motion of the operating shaft 2 by the screw feeding action of the female screw 31a and the male screw 21a on the rotor 3 side, and the valve body 14 moves in the direction of the axis L via the operating shaft 2. Thereby, the valve body 14 adjusts the opening degree of the valve port 1d, and the flow rate of the refrigerant flowing in from the joint pipe 11 and flowing out from the joint pipe 12 is controlled.

  FIG. 2 is a longitudinal sectional view of a motor-driven valve according to a second reference example. Elements that are the same as or correspond to those in FIG. In the second reference example, the valve body 14 is formed integrally with the operating shaft 2, and a valve port member 1f is fitted between the outlet port 1c and the valve chamber 1a. A valve port 1g is formed in the valve port member 1f, and an end portion of the valve port member 1f constitutes a valve seat 1f1.

  Also in the second reference example, when the rotor 3 is rotated by driving the stepping motor 10, the rotation of the rotor 3 is caused by the screw feeding action of the female screw 31a on the rotor 3 side and the male screw 21a on the working shaft 2 side. 2 is converted into a linear motion of 2 and the valve body 14 moves in the direction of the axis L via the operating shaft 2. Thereby, the valve body 14 adjusts the opening degree of the valve port 1g, and the flow rate of the refrigerant flowing in from the joint pipe 11 and flowing out from the joint pipe 12 is controlled.

  The material of the male screw member 21 and the female screw member 31 is selected in consideration of the linear expansion coefficient in the direction perpendicular to the axis L. In general, a resin material can be mixed with a reinforcing material (filler) such as carbon fiber or glass fiber, and properties such as linear expansion coefficient and thermal conductivity can be changed depending on the amount and strength of the filler to be mixed. Table 1 below shows examples of the materials of the male screw member 21 and the female screw member 31 and their linear expansion coefficients.

A combination of these materials satisfies the condition that “the linear expansion coefficient in the direction perpendicular to the axis L direction of the female screw member 31 is greater than the linear expansion coefficient in the direction perpendicular to the axis L direction of the male screw member 21”. Thus, the material of the male screw member 21 and the female screw member 31 is determined. In addition, PPS (polyphenylene sulfide) mixed with fibrous filler can give anisotropy to the linear expansion coefficient by changing the directionality of the fibrous filler, and in a direction perpendicular to the axial direction. Different linear expansion coefficients can be provided. For example, when carbon fiber is used as a filler, the linear expansion coefficient is 2.5 × 10 ^{−5 in} a certain direction, and the linear expansion coefficient in a direction perpendicular to this direction is 3.5 × 10 ^−5. it can. Depending on the amount and strength of the filler to be mixed, the linear expansion coefficient is 1.0 × 10 ^{−5 in a} certain direction, and the linear expansion coefficient in a direction perpendicular to this direction is 3.5 × 10 ^−5. is there. Therefore, the female screw member 31 is formed so that the direction in which the linear expansion coefficient is small is the axis L direction, and the direction in which the linear expansion coefficient is large is the direction perpendicular to the axis L direction. Then, the male screw member 21 is formed so that the linear expansion coefficient of the male screw member 21 in the direction perpendicular to the axis L direction is smaller than the linear expansion coefficient of the female screw member 31 in the direction perpendicular to the axis L direction. In the case where the male screw member 21 is made of stainless steel and the case where the male screw member 21 is made of brass, the materials that cannot be used for the female screw member 31 are described in the lower part of Table 1, but other than this, The materials of the member 21 and the female screw member 31 are combined.

For example, the male screw member 21 is made of stainless steel and the female screw member 31 is made of brass. Alternatively, the male screw member 21 is made of stainless steel, and the female screw member 31 is made of PPS using carbon fiber as a filler so that the linear expansion coefficient in the direction perpendicular to the axis L direction is 3.5 × 10 ⁻⁵ . Alternatively, the male screw member 21 is made of brass, and the female screw member 31 is made of PPS or PEEK (polyether ether ketone) or PI (polyimide) or a linear expansion coefficient in the direction perpendicular to the axis L direction of 3.5 × 10 ⁻⁵ or PAI (polyamideimide) is used.

The male screw member 21 is made of ceramic (zirconia) having a linear expansion coefficient of 1.05 × 10 ⁻⁵ , and the female screw member 31 has a linear expansion coefficient of 3.5 × 10 ⁻⁵ in the direction perpendicular to the axis L direction and the axis L The PPS is made of carbon fiber filler so that the linear expansion coefficient in the direction is 1.0 × 10 ⁻⁵ . If it does in this way, the linear expansion coefficient of the axial L direction of the internal thread member 31 and the linear expansion coefficient of the external thread member in the axial L direction will become equivalent, satisfying the said conditions. As a result, the expansion in the axis L direction is equivalent between the male screw member 21 and the female screw member 31, the pitch change of the male screw 21a is equal to the pitch change of the female screw 31a, and the backlash of the entire screw in the axis L direction due to the pitch change is reduced. Can be prevented.

  Table 2 below shows an example in which the material of both the male screw member 21 and the female screw member 31 is PPS.

That is, the male screw member is made of PPS using carbon fiber as a filler so that the linear expansion coefficient in the direction of the axis L is 3.5 × 10 ⁻⁵ and the linear expansion coefficient in the direction perpendicular to the axis L is 2.5 × 10 ^−5. 21 is formed. The female screw member is made of PPS using carbon fiber as a filler so that the linear expansion coefficient in the axis L direction is 2.5 × 10 ⁻⁵ and the linear expansion coefficient in the direction perpendicular to the axis L is 3.5 × 10 ^−5. 31 is formed. Thus, the above condition is satisfied.

  FIG. 3 is a diagram illustrating an example in which the male screw member 21 and the female screw member 31 are formed of a resin material using carbon fiber as a filler. The male screw member 21 is formed by aligning and mixing a carbon fiber filler 21B in a direction perpendicular to the axis L with respect to a base material 21A made of a resin material. The female screw member 31 is formed by aligning and mixing a carbon fiber filler 31B in a direction parallel to the axis L with respect to a base material 31A made of a resin material.

  By doing so, in the male screw member 21, the linear expansion coefficient in the direction perpendicular to the axis L direction of the base material 21A is reduced by the strength of the carbon fiber filler 21A, and in the female screw member 31, the line in the axis L direction of the base material 31A. The expansion coefficient is reduced by the strength of the carbon fiber filler 21A, and the linear expansion coefficient in the direction perpendicular to the axis L direction is hardly affected by the carbon fiber filler 31B. Therefore, the above conditions can be satisfied. In addition, the orientation direction of this carbon fiber filler can be set by the position of the gate at the time of resin molding, for example.

  In this way, the male screw member 21 and the female screw member 31 are made so that the linear expansion coefficient in the direction perpendicular to the axis L of the female screw member 31 is larger than the linear expansion coefficient in the direction perpendicular to the axis L of the male screw member 21. Since it forms, even if it uses in a high temperature environment, the backlash of the external thread member 21 and the internal thread member 31 can be ensured, and the stable operativity of a screw feed mechanism can be ensured.

  In the first and second reference examples, an internal thread is formed on the rotor side, and an external thread formed on the operating shaft side is disposed through the center of the internal thread on the rotor side. However, the internal thread is formed on the valve housing side. Alternatively, an operation shaft and a male screw may be formed on the rotor side, and the male screw may be disposed through the center of the female screw on the valve housing side. Also in this case, the male screw member and the female screw member are formed so that the linear expansion coefficient in the direction perpendicular to the axis of the female screw member is larger than the linear expansion coefficient in the direction perpendicular to the axis of the male screw member. The same as the reference example. Therefore, even in this embodiment, even when used in a high temperature environment, the play of the male screw member and the female screw member can be secured, and the stable operability of the screw feed mechanism can be secured.

DESCRIPTION OF SYMBOLS 1 Valve housing 1d1 Valve seat 1f1 Valve seat 14 Valve body 2 Actuating shaft 21 Male screw member 21a Male screw 3 Rotor 31 Female screw member 31a Female screw 10 Stepping motor (electric motor)

Claims (3)

A female screw provided on the valve housing side and a male screw formed on the rotor side of the electric motor and penetratingly arranged at the center of the female screw, and the rotational movement of the rotor of the electric motor is controlled by a screw between the female screw and the male screw. In the motor operated valve that opens and closes the valve by converting the linear motion of the operating shaft by the feed mechanism and moving the valve element arranged on the operating shaft with respect to the valve seat,
The material constituting the female screw and the member constituting the male screw are such that the linear expansion coefficient in the direction perpendicular to the axial direction of the female screw is greater than the linear expansion coefficient in the direction perpendicular to the axial direction of the male screw. A motor-operated valve formed by each of the above.   The member that constitutes the female screw and the member that constitutes the male screw are respectively formed of a material in which the linear expansion coefficient in the axial direction of the female screw is equal to the linear expansion coefficient in the axial direction of the male screw. The motor-operated valve according to claim 1.   2. The electric motor according to claim 1, wherein a member constituting the female screw is a resin material as a base material, and a fibrous filler is mixed in the resin material in the same direction as the axial direction of the female screw. valve.

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